Improvement of Traceability for Radiation Pyrometers in the Steel Industry

Abstract

A traceability system for radiation pyrometers has been established. In this system a radiation pyrometer is calibrated beforehand at several fixed points, and it is used as the primary standard pyrometer. In the range of 800°C-1 350°C an automatic optical pyrometer is used as the primary standard and in the range between 500°C-800°C the 0.9 μm silicon-cell pyrometer is used.
The emissivity of blackbody has been calculated by the integral equation method, and then the systematic errors have been evaluated as follows: The primary standard calibrated at the fixed points has an accuracy better than ±1K ; The secondary standard (Si-cell radiation pyrometers) has an accuracy better than ±2K, when calibrated by the primary standard. Radiation pyrometers can be calibrated by using the above secondary standard, and have an accuracy better than ±3K which is accurate enough for use in the steel industry.